Download Part I - American Chemical Society

2013 U.S. NATIONAL
CHEMISTRY OLYMPIAD
NATIONAL EXAM PART I
Prepared by the American Chemical Society Chemistry Olympiad Examinations Task Force
OLYMPIAD EXAMINATIONS TASK FORCE
Arden P. Zipp, Chair, State University of New York, Cortland, NY
James Ayers, Mesa State College, Grand Junction, CO
Peter Demmin, Amherst HS, Amherst, NY (deceased)
Marian DeWane, Centennial HS, Boise, ID
Xu Duan, Holton-Arms School, Bethesda, MD
Valerie Ferguson, Moore HS, Moore, OK
Julie Furstenau, Thomas B. Doherty HS, Colorado Springs, CO
Kimberly Gardner, United States Air Force Academy, CO
Paul Groves, South Pasadena HS, South Pasadena, CA
Preston Hayes, Glenbrook South HS, Glenbrook, IL (retired)
Jeff Hepburn, Central Academy, Des Moines, IA
David Hostage, Taft School, Watertown, CT
Adele Mouakad, St. John's School, San Juan, PR
Jane Nagurney, Scranton Preparatory School, Scranton, PA
Ronald Ragsdale, University of Utah, Salt Lake City, UT
Peter Sheridan, Colgate University, Hamilton, NY
DIRECTIONS TO THE EXAMINER – PART I
The USNCO Subcommittee is conducting a survey in an effort to determine the impact of the Olympiad program on students.
The first phase of this effort is represented by several questions added to the end of this year's exam, which should be
answered on the same Scantron sheet students use for the exam. These questions may be administered before or after the 90
minutes allotted for the exam, at your discretion, but each student should be encouraged to answer these questions.
Part I of this test is designed to be taken with a Scantron answer sheet on which the student records his or her responses. Only this
Scantron sheet is graded for a score on Part I. Testing materials, scratch paper, and the Scantron sheet should be made available to the
student only during the examination period. All testing materials including scratch paper should be turned in and kept secure until
April 15, 2013, after which tests can be returned to students and their teachers for further study.
Allow time for students to read the directions, ask questions, and fill in the requested information on the Scantron sheet. The answer
sheet must be completed using a pencil, not pen. When the student has completed Part I, or after one hour and thirty minutes have
elapsed, the student must turn in the Scantron sheet, Part I of the testing materials, and all scratch paper.
There are three parts to the National Chemistry Olympiad Examination. You have the option of administering the three parts in any
order, and you are free to schedule rest breaks between parts.
Part I
60 questions
single answer, multiple-choice
1 hour, 30 minutes
Part II
8 questions
problem-solving, explanations
1 hour, 45 minutes
Part III
2 lab questions
laboratory practical
1 hour, 30 minutes
A periodic table and other useful information are provided on page 2 for student reference.
Students should be permitted to use non-programmable calculators.
DIRECTIONS TO THE EXAMINEE – DO NOT TURN THE PAGE UNTIL DIRECTED TO DO SO. Answers to questions in
Part I must be entered on a Scantron answer sheet to be scored. Be sure to write your name on the answer sheet, an ID number is
already entered for you. Make a record of this ID number because you will use the same number on Parts II and III. Each item in
Part I consists of a question or an incomplete statement that is followed by four possible choices. Select the single choice that best
answers the question or completes the statement. Then use a pencil to blacken the space on your answer sheet next to the same letter as
your choice. You may write on the examination, but the test booklet will not be used for grading. Scores are based on the number of
correct responses. When you complete Part I (or at the end of one hour and 30 minutes), you must turn in all testing materials, scratch
paper, and your Scantron answer sheet. (Do not forget to turn in your U.S. citizenship/Green Card Holder statement before
leaving the testing site today.)
Property of ACS USNCO – Not for use as a USNCO National Exam after April 15, 2013
Distributed by the American Chemical Society, 1155 16 th Street, N.W., Washington, DC 20036
All rights reserved. Printed in U.S.A.
amount of substance
ampere
atmosphere
atomic mass unit
Avogadro constant
Celsius temperature
centi– prefix
coulomb
density
electromotive force
energy of activation
enthalpy
entropy
equilibrium constant
n
A
atm
u
NA
°C
c
C
d
E
Ea
H
S
K
ABBREVIATIONS AND SYMBOLS
Faraday constant
F molar mass
free energy
G mole
frequency
 Planck’s constant
gas constant
R pressure
gram
g rate constant
hour
h reaction quotient
joule
J second
kelvin
K speed of light
kilo– prefix
k temperature, K
liter
L time
measure of pressure mm Hg vapor pressure
milli– prefix
m volt
molal
m volume
molar
M
CONSTANTS
M
mol
h
P
k
Q
s
c
T
t
VP
V
V
R = 8.314 J•mol– •K–
1
1
R = 0.0821 L•atm•mol– •K–
1
1 F = 96,500 C•mol–
1
1 F = 96,500 J•V–1•mol–
1
1
NA = 6.022  1023 mol–
1
h = 6.626  10–34 J•s
c = 2.998  108 m•s–
0 °C = 273.15 K
1 atm = 760 mm Hg
1
EQUATIONS
E  Eo 
1
1A
1
H
RT
ln Q
nF
k  E  1 1 
ln  2   a   
 k1  R  T1 T2 
 H  1 
ln K  
   constant
 R  T 
PERIODIC TABLE OF THE ELEMENTS
18
8A
2
He
3
Li
2
2A
4
Be
13
3A
5
B
14
4A
6
C
15
5A
7
N
16
6A
8
O
17
7A
9
F
6.941
9.012
10.81
12.01
14.01
16.00
19.00
20.18
11
Na
12
Mg
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
22.99
24.31
26.98
28.09
30.97
32.07
35.45
39.95
19
K
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
1.008
4.003
10
Ne
20
Ca
3
3B
21
Sc
4
4B
22
Ti
5
5B
23
V
6
6B
24
Cr
7
7B
25
Mn
8
8B
26
Fe
9
8B
27
Co
10
8B
28
Ni
11
1B
29
Cu
12
2B
30
Zn
39.10
40.08
44.96
47.88
50.94
52.00
54.94
55.85
58.93
58.69
63.55
65.39
69.72
72.61
74.92
78.96
79.90
83.80
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
85.47
87.62
88.91
91.22
92.91
95.94
(98)
101.1
102.9
106.4
107.9
112.4
114.8
118.7
121.8
127.6
126.9
131.3
55
Cs
56
Ba
57
La
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
132.9
137.3
138.9
178.5
180.9
183.8
186.2
190.2
192.2
195.1
197.0
200.6
204.4
207.2
209.0
(209)
(210)
(222)
87
Fr
88
Ra
89
Ac
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
114
115
116
117
118
(Uut)
(Uuq)
(Uup)
(Uuh)
(Uus)
(Uuo)
(223)
(226)
(227)
(261)
(262)
(263)
(262)
(265)
(266)
(281)
(272)
(285)
(284)
(289)
(288)
(293)
(294)
(294)
Page 2
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
140.1
140.9
144.2
(145)
150.4
152.0
157.3
158.9
162.5
164.9
167.3
168.9
173.0
175.0
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr
232.0
231.0
238.0
(237)
(244)
(243)
(247)
(247)
(251)
(252)
(257)
(258)
(259)
(262)
Property of ACS USNCO – Not for use as a USNCO National Exam after April 15, 2013
DIRECTIONS

When you have selected your answer to each question, blacken the corresponding space on the answer sheet using a soft, #2
pencil. Make a heavy, full mark, but no stray marks. If you decide to change an answer, erase the unwanted mark very carefully.

There is only one correct answer to each question. Any questions for which more than one response has been blackened will not
be counted.

Your score is based solely on the number of questions you answer correctly. It is to your advantage to answer every question.
1. A reaction mixture is prepared containing 0.60 mol of
aluminum and 1.20 mol of manganese dioxide. The
mixture is heated until one of the reactants has been
completely consumed according to the equation:
2 Al + 3 MnO2  3 Mn + Al2O3
What quantity of which reactant remains uncombined?
(A) 0.20 mol Al
(B) 0.40 mol Al
(C) 0.30 mol MnO2
(D) 0.60 mol MnO2
2. A solution with a mass of 1.263 g containing an unknown
amount of potassium ions was treated with excess sodium
tetraphenylborate to precipitate 1.003 g of KB(C6H5)4
(M = 358.33). What is the mass percentage of potassium
in the original solution?
(A) 8.67%
(B) 9.16%
(C) 10.9%
(D) 13.8%
3. A typical polyethylene grocery bag weighs 12.4 g. How
many metric tons of CO2 would be released into the
atmosphere if the 102 billion bags used in one year in the
United States were burned? [1 metric ton = 1000 kg]
(A) 4.52  10
4
(C) 3.98  106
(B) 1.99  10
6
(D) 3.98  109
4. Which mixture of water and H2SO4 represents a solution
with a concentration that is closest to 30% by mass
H2SO4?
(A) 30 g H2SO4 + 100 g H2O
(B) 1 mol H2SO4 + 200 g H2O
(C) 30 mol H2SO4 + 0.70 kg H2O
(D) 0.30 mol H2SO4 + 0.70 mol H2O
5. How would the freezing point depression of a 0.05 m
CaCl2 solution compare with that of a NaCl solution? It
would be
6. What is the mole fraction of CH3OH in an aqueous
solution that is 12.0 m in CH3OH?
(A) 0.178
(C) 0.400
(D) 0.667
7. Three different oxides of nitrogen each contain 7.00 g of
nitrogen and weigh 15.0 g, 23.0 g and 19.0 g,
respectively. What are their empirical formulas?
(A) NO, NO2, N2O3
(B) NO, N2O3, N2O5
(C) N2O, NO2, N2O5
(D) NO2, N2O3, N2O5
8. Which substance is used in self-contained breathing
equipment because it absorbs exhaled CO2 and H2O and
releases O2 gas?
(A) KO2
(B) Na2O2
(C) NaOH
(D) Li2O
9. A sample of a white solid is known to be NaHCO3,
AgNO3, Na2S, or CaBr2. Which 0.1 M aqueous solution
can be used to confirm the identity of the solid?
(A) NH3(aq)
(B) HCl(aq)
(C) NaOH(aq)
(D) KCl(aq)
10. The infrared frequency of the CX vibration for CH3X
depends on which of the following?
I. mass of X
II. strength of the CX bond
III. type of CX vibration (stretch or bend)
(A) I. only
(B) II. only
(C) II. and III. only
(D) I., II. and III.
–
11. When the permanganate ion, MnO4 , acts as an oxidizing
agent it forms different products depending on the pH of
the solution. Which species correspond to the conditions
listed?
A
B
C
D
(A) less than that for a 0.10 m NaCl solution.
(B) between that for a 0.10 m NaCl solution and a 0.20 m
NaCl solution.
(C) between that for a 0.20 m NaCl solution and a 0.30 m
NaCl solution.
(B) 0.216
(A) A
acidic
Mn2+
Mn2+
MnO2
Mn2+
(B) B
basic
Mn(OH)2
–
MnO42
–
MnO42
Mn(OH)2
(C) C
neutral
MnO2
MnO2
Mn(OH)2
–
MnO42
(D) D
(D) greater than that for a 0.30 m NaCl solution.
Property of ACS USNCO – Not for use as a USNCO National Exam after April 15, 2013
Page 3
12. In an experiment to verify the value of absolute zero, a
student is instructed to measure the volume of He in a 10mL syringe at 10 °C intervals between 0 ° and 100 °C.
She is told to plot the volume versus temperature and to
extrapolate this graph to zero volume and read the
resulting temperature. Which modification of the
experimental procedure will give the best value for
absolute zero?
17.
(A) Correcting each measured volume to one atmosphere
pressure before plotting.
The phase diagram for sulfur is shown above. Which
statement about this diagram is correct?
(B) Doubling the number of temperature-volume values
between 0 ° and 100 °C.
(A) The critical point is above 154 °C and 103 atm.
(C) Using a thermometer that can measure temperature to
+ 0.10 °C between 0° and 100 °C.
(B) There are only two triple points in this diagram.
(C) Monoclinic sulfur is more dense than rhombic
sulfur at any temperature.
(D) Measuring the volume of He in the syringe at – 40 °C
and – 80 °C.
13. The Henry’s law constant for oxygen gas in water at
–
–
25 °C kO2 is 1.3×10 3 M •atm 1. What is the partial
pressure of O2 above a solution at 25 °C with an O2
–
concentration of 2.3×10 4 M at equilibrium?
(A) 5.7 atm
(B) 0.18 atm
–3
(C) 1.3×10 atm
(D) 3.0×10
–7
(D) Monoclinic sulfur forms rhombic sulfur at higher
pressure or lower temperature.
18. What is the principal difference between crystalline and
amorphous solids?
crystalline solids
amorphous solids
atm
14. A sample of gas measured at 20 °C and 4.0 atm is heated
to 40 °C at constant volume. Which statement(s) is (are)
true of the gas after heating relative to its initial state?
I.
II.
III.
IV.
The average molecular kinetic energy is increased.
The average molecular speed is unchanged.
The pressure of the gas is increased to 8.0 atm.
The number of molecular collisions per second is
unchanged.
(A) I. only
(B) I. and IV. only
(C) II. and III. only
(D) II. and IV. only
15. Under what conditions does the behavior of real gases
deviate most from that predicted by the ideal gas law?
(A) low P, low T
(B) high P, low T
(C) low P, high T
(D) high P, high T
16. When 0.25 L of liquid nitrogen (d = 0.807 g/mL) is
vaporized, what volume does the resulting gas occupy at
25 °C and 5.00 atm?
(A) 71 L
Page 4
(B) 54 L
(C) 35 L
(D) 32 L
(A) ionic bonding
covalent bonding
(B) higher molar masses
lower molar masses
(C) stoichiometric solids
non-stoichiometric solids
(D) long-range order
lack of long-range order
19. Which is (are) state properties?
I. enthalpy
II. heat
III. volume
20.
(A) I. only
(B) II. only
(C) I. and III. only
(D) II. and III. only
HNO2(l) + NaCl(s)  HCl(g) + NaNO2(s)
Calculate the ∆H˚ value for the reaction above from the
information below.
–
Reaction
∆H˚ kJ•mol 1
NO(g) + NO2(g) + Na2O(s)  2NaNO2(s)
– 427.0
NO(g) + NO2(g)  N2O(g) + O2(g)
– 43.0
2NaCl(s) + H2O(l)  2HCl(g) + Na2O(s)
507.0
2HNO2(l)  N2O(g) + O2(g) + H2O(l)
34.0
(A) 157 kJ
(B) 78.5 kJ
(C) –78.5 kJ
(D) –157 kJ
21. For which reaction(s) is the ∆H value close to the ∆E
value?
I. CH4(g) + 2 O2(g)  CO(g) + 2 H2O(l)
II. C2H4(g) + 3 O2(g)  2 CO2(g) + 2 H2O(g)
(A) I. only
(B) II. only
(C) Both I. and II.
(D) Neither I. nor II.
Property of ACS USNCO – Not for use as a USNCO National Exam after April 15, 2013
22. What is the value of ∆S˚ for the reaction below?
Fe2O3(s) + 3 CO(g)  2 Fe(s) + 3 CO2(g)
Substance
–
–
S˚ (J•mol 1•K 1)
(A) –44.0 J•K
(C) 15.5 J•K
Fe(s)
27.3
–1
Fe2O3(s)
87.4
CO(g)
197.7
(B) –11.8 J•K
–1
28. Which graph is linear for a reaction that is second order
in [A]?
(D) 42.8 J•K
CO2(g)
213.8
(B) 77.9 °C
(C) 506 °C
(D) 779 °C
–1
(C) 14.7 kJ•mol
(B) –14.7 kJ•mol
–1
29. The reaction of nitrogen dioxide with carbon monoxide
NO2(g) + CO(g)  CO2(g) + NO(g)
has been studied and the following mechanism has been
proposed:
NO2(g) + NO2(g)  NO3(g) + NO(g) slow
NO3(g) + CO(g)  NO2(g) + CO2(g) fast
What rate law corresponds to this mechanism?
–1
(C) –0.275 M•min
(A) 4.46  10–5 M–1•.s–1
(B) 8.54  10–5 M–1•.s–1
(C) 8.52  10–4 M–1•.s–1
(D) 8.54  10–3 M–1•.s–1
31. For which reaction will Kp be larger than Kc at 25 °C?
(A) CO2(g) + C(s)
(B) 2 NO2(g)
–1
(B) –0.880 M•min
2 CO(g)
N2O4(g)
(C) H2(g) + F2(g)
–1
(D) –0.220 M•min
26. A first-order reaction has a rate constant of k = 0.320
–
min 1. For an initial reactant concentration of 1.22 M,
how long does it take for its concentration to fall to 0.150
M?
–
45 °C and an activation energy, Ea = 90.8 kJ. What is the
value of k at 25 °C?
–1
–1
(D) Rate = k[NO2]2[CO]
–
–1
25. Ammonia reacts with oxygen according to the equation:
4 NH3(g) + 5 O2(g)  4 NO(g) + 6 H2O(l)
In an experiment in which the rate of change of nitric
–
oxide is found to be 1.10 M•min 1, what is the rate of
change of oxygen gas?
(B) Rate = k[NO2][CO]
2
30. A reaction has a rate constant k = 8.54  10-4 M 1•.s 1 at
(D) 175 kJ•mol
(A) –1.38 M•min
(D) 1/[A] vs time
(C) Rate = k[NO2]
–
(A) –175 kJ•mol
(C) [A]2 vs time
(A) Rate = k[NO2]
24. The Ksp for Al(OH)3 is 2.0 x 10 31. What is the value of
∆G˚ for the precipitation of Al(OH)3 at 25 °C?
–
Al3+(aq) + 3 OH (aq)  Al(OH)3(s)
–1
(B) ln[A] vs time
–1
23. What is the temperature at which the reaction below is at
equilibrium?
2 NO(g) + O2(g)  2 NO2(g)
–
–
–
˚rxn = –113 kJ•mol 1
S˚rxn = –145 J•mol 1•K 1
(A) –195 °C
(A) [A] vs time
2 HF(g)
(D) O3(g) + NO(g)
32.
NO2(g) + O2(g)
(A) 0.671 min
(B) 2.60 min
2 SO3(g)
2 SO2(g) + O2(g)
When SO3(g) is added to a sealed bulb at a pressure of
2.0 atm, it undergoes the reaction above. At equilibrium,
76% of the SO3(g) has reacted. What is the value of Kp at
this temperature?
(C) 6.55 min
(D) 25.4 min
(A) 15
27. Iodine monochloride reacts with hydrogen according to
the equation:
2 ICl(g) + H2(g)  I2(g) + 2 HCl(g)
The rate data below have been obtained.
–1
[ICl], M
[H2], M
Initial Rate, M•s
0.10
0.10
0.030
0.20
0.10
0.060
0.10
0.050
0.015
What is the rate law for the reaction?
(A) Rate = k[ICl][H2]
(B) Rate = k[ICl]2[H2]
(C) Rate = k[ICl][H2]1/2
(D) Rate = k[ICl]2[H2]1/2
(B) 7.6
(C) 3.8
(D) 2.4
33. The pH of pure water at 50 °C is 6.63. What is the value
of Kw at 50 °C?
(A) 1.8  10–15
(B) 1.0  10–14
(C) 5.5  10–14
(D) 2.2  10–13
34. Alanine, H2NCH(CH3)CO2H, has Ka = 4.5  10–3 and
–
Kb = 7.4  10 5. Which species has the highest
concentration at a pH of 7.00 in H2O?
(A) H2NCH(CH3)CO2H
(C)
–
H2NCH(CH3)CO2
Property of ACS USNCO – Not for use as a USNCO National Exam after April 15, 2013
(B)
+
(D)
+
H3NCH(CH3)CO2H
H3NCH(CH3)CO2
–
Page 5
35. What is the pH of the solution formed by mixing 25.0 mL
of a 0.15 M solution of NH3 with 25.0 mL of 0.12 M
–
HCl? (Kb for NH3 = 1.8  10 5)
(A) 7.4  10–5 M
(B) 5.9  10–5 M
Half-Reaction
E°, V
–
0.340
Cu (aq) + 2e  Cu(s)
–
2+
–0.136
Sn (aq) + 2e  Sn(s)
–
–0.440
Fe2+(aq) + 2e  Fe(s)
–
2+
–0.763
Zn (aq) + 2e  Zn(s)
–
–2.37
Mg2+(aq) + 2e  Mg(s)
According to the standard reduction potentials above,
cathodic protection of iron can be achieved by
(C) 4.7  10–5 M
(D) 3.7  10–5 M
(A) Cu(s) only.
(B) Cu(s) and Sn(s) only.
(C) Mg(s) only.
(D) Mg(s) and Zn(s) only.
(A) 4.14
(B) 5.34
(C) 8.65
(D) 9.86
–
36. What is the [OH ] in a suspension of the antacid
–
Mg(OH)2?
(Ksp = 2.06  10 13)
37. When the equation below is balanced correctly using the
simplest whole number coefficients, what is the
coefficient for CO2(g)?
–
__ Cr2O72 (aq) + __ H2C2O4(aq) + __ H+(aq) 
__Cr3+(aq) + __ CO2(g) + __ H2O(l)
(A) 4
38.
42.
(B) 6
(C) 8
(D) 12
–
Au3+ + 3e  Au(s)
E° = 1.50 V
–
Ag+ + e  Ag(s)
E° = 0.80 V
–
Cu2+ + 2e  Cu(s)
E° = 0.34 V
According to the standard reduction potentials above, a
substance that can oxidize only one of these metals must
have an E° value
(A) less than 0.34 V.
(B) between 0.34 and 0.80 V.
(C) between 0.80 and 1.50 V.
(D) greater than 1.50 V.
39. What is the ∆G˚ value for the electrochemical cell below?
–
Cu(s) | Cu2+(aq) || NO3 (aq) | NO(s) | Pt(s)
Half-Reaction
–
–
NO3 (aq) + 4H+(aq) + 3e  NO(g) +2H2O(l)
–
2+
Cu (aq) + 2e  Cu(s)
(A) –753 kJ
(B) –359 kJ
(C) –179 kJ
(D) –59.8 kJ
E°, V
0.960
0.340
40. An aqueous solution of CuSO4 is electrolyzed for 1.50
hours with a current of 2.50 amps. What mass of copper
metal is formed?
(A) 8.88 g
(B) 4.44 g
(C) 0.296 g (D) 0.0741 g
41. Under what conditions is the Nernst equation used to
calculate cell potential voltages in a voltaic cell?
2+
43. Which is an acceptable set of quantum numbers for an
electron?
(A) 1, 1, 0, 1/2
(B) 2, 1, 0, 0
(C) 2, 1, –1, –1/2
(D) 3, 2, –3, 1/2
44. Which orbital has the most radial nodes?
(A) 4s
(B) 4p
(C) 4d
(D) 4f
45. Ionization energies vary from left to right across the
periodic table. Factors that contribute to this variation
include which of the following?
I. changes in the nuclear charge
II. differences in shielding by valence electrons
III. differences in shielding by core electrons
(A) I. only
(B) III. only
(C) I. and II. only
(D) I., II. and III.
46. Which gaseous ion has exactly three unpaired electrons?
(A) Fe3+
(B) Ni2+
(C) Ti4+
(D) V2+
47. Which element has the highest second ionization energy?
(A) Na
(B) Mg
(C) S
(D) F
48. The ions below are listed in order of increasing radii
except
(A) Al3+ < Mg2+ < Na+
–
–
(C) Cl < Br < I
–
–
–
(B) K+ < Cl < Se2
–
–
(D) O2 < F < Na+
49. How many sigma bonds are present in P4?
(A) 3
(B) 4
(C) 5
(D) 6
50. Using VSEPR theory, the molecular structure of IF5 is
best described as
(A) non-standard concentrations only
(A) octahedral
(B) square pyramidal
(B) non-spontaneous reactions only
(C) trigonal bipyramidal
(D) trigonal pyramidal
(C) reactions at equilibrium only
(D) reactions of ions with the same charge only
Page 6
51. What is the formal charge on the oxygen atom in :C:::O:?
(A) +1
(B) 0
(C) –1
(D) –2
Property of ACS USNCO – Not for use as a USNCO National Exam after April 15, 2013
–
52. Which is a valid Lewis structure for the nitrate ion, NO3 ?
(A)
(B)
(C)
(A)
(B)
(C)
(D)
(D)
53. Based on molecular orbital theory, which species has the
highest bond order?
(A) O2
59. What is the product when two molecules of ethanal,
CH3CHO, undergo an aldol condensation ?
+
–
(B) O2
(C) O2
(D)
–
O22
54. How many carbon atoms can be described as sp2
hybridized in this molecule?
60. Which molecule will have the longest wavelength
absorbance maximum?
(A)
(B)
(C)
(A) 0
(B) 1
(C) 2
(D) 3
55. Which compound contains four co-linear carbon atoms?
(A) butane
(B) cis-2-butene
(C) trans-2 butene
(D) 2-butyne
56. Which substance can exist in boat and chair
configurations?
(A) benzene
(B) cyclohexane
(C) cyclopentadiene
(D) naphthalene
57. Which of the numbered carbons in nicotine is chiral
(stereogenic)?
4
1
(A) 1
3
(B) 2
END OF TEST
When you have finished answering this examination or time has
been called by the Examiner, please provide responses to the
following 4 items. Your answers will not affect your score on the
exam but will help with a study being conducted by the U.S.
National Chemistry Olympiad (USNCO) Subcommittee.
61. The amount of time I spend doing experiments in the
laboratory per week on average during my chemistry
course was/is?
(A) less than ½ hour.
(B) between ½ and 1 hour.
(C) between 1 and 2 hours.
(D) more than 2 hours.
The following questions should be answered using the scale
(A) Strongly agree
(B) Agree
(C) Disagree
(D) Strongly disagree
N
2
N
(D)
CH3
(C) 3
(D) 4
58. All of the following are monosaccharides except
(A) fructose
(B) glucose
(C) ribose
(D) sucrose
62. As a result of my participation in the USNCO program,
I plan to study more chemistry.
63. As a result of my participation in the USNCO program,
I plan to major in chemistry in college.
64. As a result of my participation in the USNCO program,
I have a more positive view of chemistry than I did before
participating.
Property of ACS USNCO – Not for use as a USNCO National Exam after April 15, 2013
Page 7
Olympiad 2013
USNCO National Exam Part I
KEY
Number
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Answer
C
A
C
B
A
A
A
A
B
D
B
D
B
A
B
C
D
D
C
B
B
C
C
A
A
C
A
D
C
B
Number
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
Answer
A
B
C
D
C
A
B
B
B
B
A
D
C
A
C
D
A
D
D
B
A
B
A
D
D
B
B
D
D
A